Feasibility discrimination and experimental verification of upward mining in close-range coal seam groups

When making preliminary judgments on the feasibility of upward mining using computational methods, there are often conflicting results. Based on the “three zone” discrimination method and ratio analysis, and the statistical results of typical cases of upward mining, a control coefficient E is defined to evaluate the degree of control of the key layer towards the upward mining coal seam. This proposes a discrimination method for upward mining that considers the control effect of the key layer. Based on the occurrence conditions of coal seams 1 and 2 in the fifth division of Zaoquan Coal Mine, a long×wide×height=2 000 mm×200 mm×1 800 mm plane stress similarity model with a dip angle of 26° is used to validate the judgment method proposed in this paper. The results indicate that coal seam 1 is located outside the collapse zone of coal seam 2 mining, maintaining a good layered form and continuity, without any stepped subsidence. Coal seam 1 can be mined upwards after coal seam 2 mining, further supplementing and enriching the preliminary determination method for the feasibility of upward mining.